Can a technological singularity only occur with superintelligence?
That would be a no for speed or strength, if you have a super strong entity but it cannot research new materials, it will be quickly limited, same thing for speed, Basically, you need something out of their field to improve them, which makes a runaway improvement impossible. 

Though, we already have super strong and super fast machines, those are cars, trucks, hydraulic presses, industrial exoskeletons etc... But, even though we can build better ones through the use of the old ones, we still need to research stuff that can't be improved by old ones.

What we need for a singularity is a field where an improvement in it makes further improvement easier. And I don't know a field where this doesn't involve intelligence. 
If there is one, that may be possible to have a non intelligence driven singularity there.